Breeding of male sterile rice with the backgrounds of Korean cultivars using the Chinese WA cytoplasm

Thirty nine Korean rice cultivars were crossed to the Chinese male sterile rice with the wild abortive(WA) cytoplasm V20 A and/or Zhen Shan 97A.After growing the F₁s of these crosses in greenhouse condition, the seed set percent was observed. The cultivars Tongil, Tongilchal, Suweon 290, Suweon 296, Suweon 304, Suweon 310, HR 1619-6-2-1-5-2, WX 154 and 020530 appeared to be maintainers, and the cultivars Taebaek, Suweon 294, Suweon 312, Suweon 314, Milyang 30, Milyang 46, Milyang 54, Milyang 56, Milyang 59 and Iri 349 were revealed to be good restorers for the WA cytoplasm. The five maintainer cultivars HR 1619-6-2-1-5-2, Suweon 296, Suweon 304, Tongil and Tongilchal were backcrossed five times to the WA cytoplasm. The selfed seed set of these BC₄s ranged from 0 to 0.2%. When the agronomic characters of these BC₄ male sterile lines and their maintainers were compared, no differences were found in heading date, number of florets per panicle, number of panicles per hill and length of panicle in the male sterile lines HR 1619A, Suweon 296 A and Suweon 304 A. When the male sterile lines and their maintainers were grown in alternate rows at 30×15 cm spacing in field condition, the male sterile line HR 1619A showed 10.8% outcrossing, Suweon 304A 4.5% and Suweon 296A 2.9%, while the Chinese male sterile rice Zhen Shan 97A showed 18.8%.